Opposites do attract as 'stressed men make odd sexual decisions', study suggests

Opposites really do attract in people, according to scientists who researched the psychology of sexual attraction.

The study could explain why some couples end up together for example Nicholas Sarkozy, the French President and his wife Carla Bruni-Sarkozy.

Or Tom Cruise and Katie Holmes Photo: GETTY

Or Michael Douglas and Catherine Zeta-Jones. Photo: REUTERS

Researchers in Germany discovered that stressed men made unconventional choices in sexual preferences.

Scientists at the University of Trier found that young men who were under pressure preferred erotic pictures of female nudes who were had the opposite facial expressions to themselves.

The study, reported in the journal Proceedings of the Royal Society B, also found that other participants who were more relaxed were attracted to females who had similar features.

It could explain why some couples who look different, end up together for example Nicholas Sarkozy, the French President and his wife Carla Bruni-Sarkozy – currently the subject of affair rumours – actors Tom Cruise and Katie Holmes and Michael Douglas and Catherine Zeta Jones.

Previous studies have found that men and women who fall in love tend to resemble each other in many ways, especially in facial characteristics.

"Our findings show that stress affects human mating preferences: unstressed individuals showed the expected preference for similar mates but stressed individuals seem to prefer dissimilar mates,” said Johanna Lass-Hennemann, a psychobiologist who led the study.

“Our results provide further support for facial self resemblance as a potential modulator of sexual attractiveness.

"Furthermore, our study is the first to show that stress influences human mating preferences, and provides further support for the influence of stress on mate choice and sexual behaviour."

Acting on a hunch gained from experience with lab animals, the scientists explored whether a man responded differently to a woman when he was stressed.

They recruited 50 local students, all slim and healthy, and divided them into two groups.

The students were randomly asked to either place a hand in icy water or the more pleasant alternative of warm water at normal body temperature.

Their stress ratings were measured using saliva, heart rate and blood pressure tests.

All the students were connected to electrodes measuring tiny muscle movements around the eye, which are known as the "startle reflex" that we give when we look at an object of interest.

They were then asked to look at 40 computer images of young women – 30 of them erotic nudes of girls gazing at the observer and 10 of them neutral – while the "startle reflex" spies did their job.

Men who had not been stressed showed a marked preference to women whose faces most resembled their own.

But men in the stressed group bypassed the close-resembling women and showed a preference for women who were dissimilar to themselves.

Past studies suggest that people tend to find self-resembling faces more trustworthy than dissimilar faces.

This could explain why some men pursue a long-term relationship with more well built women who look like them.

But there is also evidence that people who are stressed have more short-term relationships than unstressed counterparts.

The more sexual partners you have, the more chances you have of extending your genetic lineage, which would explain why stressed men bucked the trend.